a failed fuel pump, and it REALLY sucks to drop the tank.
Well here's how i did mine.

The size of the hatch is 9" x 16" bigger than you need but i didn't want to screw around. Plus i mounted 2 extra filters there, on on the pressure and on on the return line.NOTE: My jeep is VERY non-stock.

The placement of the hatch is centered between the fenderwells and 6" from the back of the tub. Measurement taken with the tailgate open and from the outside edge of the tub.

I drilled a 1/2" hole in each of the 4-corners I wanted of the hatch size for start/end points. Then using a sawzall with a 6" blade and being careful to keep it at a shallow angle to avoid cutting the tank i connected the dots.
There is some structure under there (channels seen in picture) so take your time, and vary depth carefully.
When all was done i riveted a standard 3" hinge to one side and took a "repair plate" (also could be called a joist plate, nailer plate etc) from the hard ware section because it was nice and thin with a bunch of holes pre-drilled to use as a stop for the hatch.

Special Note: When replacing a fuel pump it's a GOOD idea (if not stated by the manufacturer) to replace both your fuel filter and strainer/filter sock in the tank.
Also check all connections before you close it up, it sucks to bolt it back down and have it not work because you forgot a connection

I also ran a dedicated ground from the frame the a bolt on the plate, as even with is a 95 in 2001 when i re-did all of it it was a bit rusty and you fuel pump and sending unit gets it ground from the cover plate.